Source / episode info

• **Episode:**219
• **Title:**Divine Intervention Episode 219 – USMLE Step 2CK Rapid Review Series 33.
• **Published:**2020-03-06
• Source:Episode page

One-liner

This episode provides a rapid review covering advanced topics including Budd-Chiari syndrome and hemodynamic localization; the differential diagnosis of myocarditis/cardiomyopathy; infectious workups (CMV vs. EBV); calcification patterns in various organs; oxygen content abnormalities; V/Q mismatch principles, and the systemic effects of non-selective beta-blockers like propranolol.

High-yield summary

• Budd-Chiari Syndrome: Elevated hepatic venous pressure with normal right atrial (RA) and right ventricular (RV) pressures, typically due to hepatic vein thrombosis. Risk factors include OCP use or polycythemia.
• Oxygen Content ({CaO}_2) Analysis: If {CaO}_2 is low but PaO2 and {SaO}_2 are normal, the primary cause is likely anemia (low hemoglobin). Low {SaO}_2 with normal PaO2 suggests CO or cyanide poisoning.
• V/Q Mismatch: A shunt means blood flows through lung regions that are perfused but not ventilated (e.g., VSD); dead space means lung regions are ventilated but not perfused (e.g., PE).
• Infiltrative Pathology: Lymphocytic infiltrates in the small intestine suggest Celiac disease; lymphoid follicles/infiltration in the thyroid suggests Hashimoto's, increasing lymphoma risk.
• Pharmacology (-blockers): Non-selective -blockers (Propranolol) decrease cardiac output and RAAS by blocking _1 receptors, but they increase SVR by blocking _2 receptors, thus raising diastolic blood pressure.

Learning objectives

• Differentiate the hemodynamic consequences of hepatic vein obstruction versus pulmonary capillary wedge pressure elevation.
• Recognize the classic clinical and laboratory presentations associated with viral myocarditis (e.g., Coxsackie virus).
• Master the differential diagnosis of atypical mononucleosis syndrome, particularly in immunocompromised hosts (CMV vs. EBV).
• Interpret gas exchange abnormalities to distinguish between anemia, shunt, dead space, and hypoventilation.
• Apply knowledge of \beta-blocker pharmacology, specifically differentiating selective (\beta_1) from non-selective (\beta_2 blockade) effects on cardiovascular function.

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